Broadly, research in Dr. McCarthy's lab follows from two main questions: How do trees and forests respond to environmental changes? And, conversely, How can they be managed to moderate environmental changes?

As humans exert greater influence on global cycles, it becomes increasingly important to resolve the effects of these changes on both natural and highly managed systems. Dr. McCarthy's research uses physiological and ecosystem ecology to explore how tree and forest-scale water and carbon cycle processes respond to global change factors, including changes in water availability, extreme weather events, elevated atmospheric CO2, and urbanization.

Her work on the Oklahoma NSF EPSCoR research project will aid in the establishment of a first-of-its-kind, statewide, socio-ecological observatory.

Other recent research projects include:

Carbon storage in forests with increased CO2 levels

Forested ecosystems are the dominant terrestrial sink for carbon, making their potential to slow the rise of atmospheric carbon dioxide (CO2) levels of great interest. Determining future carbon sinks requires accurate information on the current carbon storage capacity of forests, as well as forest responses to increased atmospheric CO2 against the background of a changing climate. For several decades studies have focused on aspects of the carbon cycle of trees, and more recently ecosystems, exposed to elevated CO2, finding on average that photosynthesis and growth are enhanced. Despite the attention given to this issue, much of the focus has been on broad averages that may not capture all of the variation inherent in a landscape with uneven nutrient and water availability. My research has focused on the spatial and temporal variation in CO2 response, building a quantitative framework allowing CO2-induced enhancement of growth or carbon storage to be considered in the context of the availability of other resources.

Tree function and ecosystem services in urban forests

As populations become more urbanized, an increasing number of people live in systems whose fundamental processes are shaped almost entirely by humans. These highly managed systems are of growing interest due to recognition that trees can have large impacts on their surroundings and may be useful for mitigating urban heat island effects, storm water runoff, atmospheric CO2 emissions and pollution, and energy expenditures. But, trees may also have environmental costs, such as high water use in water-limited regions. Urban ecosystems are not only interesting ecosystems in their own right, they also result in “common garden” scenarios in which unique assemblages of species can be studied under the same environmental conditions, and are “natural laboratories” of global change, as they already feature altered water supplies and increased CO2, temperature, nutrient supplies, and air pollutants. Thus, studying urban tree function can also give insight on future tree function, adaptability, and what competitive advantages may emerge as trees in different environments are exposed to climatic shifts. By quantifying tradeoffs between water use and carbon uptake, my research aims to understand how trees (frequently non-native) function in stressful environments, as well as improving the ability of humans to manage these systems in ways that maximize human benefits (such as mitigating pollution, energy usage and urban heat island effects).

Teaching Responsibilities:

PBIO 6484: Plant Physiological Ecology

PBIO 3453: Principles of Plant Ecology

PBIO 3452: Methods in Plant Ecology

Research Assistants Funded by EPSCoR:

Jonathan Giddens (Graduate Student)Dept. of Microbiology and Plant Biology, University of Oklahoma Research Focus: Obtaining field measurements, and analyzing and logging the data; training and supervising others in the field.Email: jongiddens@ou.edu

This material is based on work supported by the National Science Foundation under Grant No. OIA-1301789. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or Oklahoma State Regents for Higher Education.